LXR linux/arch/arm/mm/highmem.c

   1/*
   2 * arch/arm/mm/highmem.c -- ARM highmem support
   3 *
   4 * Author:      Nicolas Pitre
   5 * Created:     september 8, 2008
   6 * Copyright:   Marvell Semiconductors Inc.
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 */
  12
  13#include <linux/module.h>
  14#include <linux/highmem.h>
  15#include <linux/interrupt.h>
  16#include <asm/fixmap.h>
  17#include <asm/cacheflush.h>
  18#include <asm/tlbflush.h>
  19#include "mm.h"
  20
  21static inline void set_fixmap_pte(int idx, pte_t pte)
  22{
  23        unsigned long vaddr = __fix_to_virt(idx);
  24        pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
  25
  26        set_pte_ext(ptep, pte, 0);
  27        local_flush_tlb_kernel_page(vaddr);
  28}
  29
  30static inline pte_t get_fixmap_pte(unsigned long vaddr)
  31{
  32        pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
  33
  34        return *ptep;
  35}
  36
  37void *kmap(struct page *page)
  38{
  39        might_sleep();
  40        if (!PageHighMem(page))
  41                return page_address(page);
  42        return kmap_high(page);
  43}
  44EXPORT_SYMBOL(kmap);
  45
  46void kunmap(struct page *page)
  47{
  48        BUG_ON(in_interrupt());
  49        if (!PageHighMem(page))
  50                return;
  51        kunmap_high(page);
  52}
  53EXPORT_SYMBOL(kunmap);
  54
  55void *kmap_atomic(struct page *page)
  56{
  57        unsigned int idx;
  58        unsigned long vaddr;
  59        void *kmap;
  60        int type;
  61
  62        preempt_disable();
  63        pagefault_disable();
  64        if (!PageHighMem(page))
  65                return page_address(page);
  66
  67#ifdef CONFIG_DEBUG_HIGHMEM
  68        /*
  69         * There is no cache coherency issue when non VIVT, so force the
  70         * dedicated kmap usage for better debugging purposes in that case.
  71         */
  72        if (!cache_is_vivt())
  73                kmap = NULL;
  74        else
  75#endif
  76                kmap = kmap_high_get(page);
  77        if (kmap)
  78                return kmap;
  79
  80        type = kmap_atomic_idx_push();
  81
  82        idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
  83        vaddr = __fix_to_virt(idx);
  84#ifdef CONFIG_DEBUG_HIGHMEM
  85        /*
  86         * With debugging enabled, kunmap_atomic forces that entry to 0.
  87         * Make sure it was indeed properly unmapped.
  88         */
  89        BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
  90#endif
  91        /*
  92         * When debugging is off, kunmap_atomic leaves the previous mapping
  93         * in place, so the contained TLB flush ensures the TLB is updated
  94         * with the new mapping.
  95         */
  96        set_fixmap_pte(idx, mk_pte(page, kmap_prot));
  97
  98        return (void *)vaddr;
  99}
 100EXPORT_SYMBOL(kmap_atomic);
 101
 102void __kunmap_atomic(void *kvaddr)
 103{
 104        unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 105        int idx, type;
 106
 107        if (kvaddr >= (void *)FIXADDR_START) {
 108                type = kmap_atomic_idx();
 109                idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
 110
 111                if (cache_is_vivt())
 112                        __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 113#ifdef CONFIG_DEBUG_HIGHMEM
 114                BUG_ON(vaddr != __fix_to_virt(idx));
 115                set_fixmap_pte(idx, __pte(0));
 116#else
 117                (void) idx;  /* to kill a warning */
 118#endif
 119                kmap_atomic_idx_pop();
 120        } else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
 121                /* this address was obtained through kmap_high_get() */
 122                kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
 123        }
 124        pagefault_enable();
 125        preempt_enable();
 126}
 127EXPORT_SYMBOL(__kunmap_atomic);
 128
 129void *kmap_atomic_pfn(unsigned long pfn)
 130{
 131        unsigned long vaddr;
 132        int idx, type;
 133        struct page *page = pfn_to_page(pfn);
 134
 135        preempt_disable();
 136        pagefault_disable();
 137        if (!PageHighMem(page))
 138                return page_address(page);
 139
 140        type = kmap_atomic_idx_push();
 141        idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
 142        vaddr = __fix_to_virt(idx);
 143#ifdef CONFIG_DEBUG_HIGHMEM
 144        BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
 145#endif
 146        set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
 147
 148        return (void *)vaddr;
 149}
 150